1. Field of the Invention
The present invention relates to an automatic transmission switch in which contacts come into contact with each other and separate from each other according to a switching operation of a shift lever of an automatic transmission.
2. Description of the Related Art
In a conventional automobile having an automatic transmission (so-called automatic car), one of a plurality of ranges can be selected by a switching operation of a shift lever. For example, the ranges are a parking range (hereinafter, P range), a reverse range (hereinafter, R range), a neutral range (hereinafter, N range), a drive range (hereinafter, D range), two-continuous range and one-continuous range (hereinafter, L range). An automobile of this kind includes an automatic transmission switch in which contacts come into contact with each other and separate from each other according to a selected range.
For example, as shown in FIG. 1, an automatic transmission switch 101 includes a fixed member 102 fixed to a vehicle body (not shown) of the automobile, a shaft 104 pivotally supported by a bearing hole 103 formed in a portion of the fixed member 102, and a movable member 105 which is fixed to the shaft 104 and supported by the fixed member 102 such that the movable member 105 can turn around a center axis (turning axis) of the shaft 104 extending along a longitudinal direction of the shaft 104. The movable member 105 is connected to an automatic transmission (not shown). The shaft 104 turns in the bearing hole 103 according to a switching operation of a shift lever (not shown), and the movable member 105 turns with respect to the fixed member 102 and switches over the ranges.
As shown in FIG. 2, a fixed-side contact 110 is disposed on a surface of the fixed member 102 opposed to the movable member 105. Movable-side contacts 111 are disposed on a surface of the movable member 105 opposed to the fixed member 102. The movable-side contacts 111 come into contact with and separate from the fixed-side contact 110. The fixed-side contact 110 includes an intermittent contact portion with respect to the movable-side contacts 111. The contact portion extends in a moving direction of the movable member 105. When the movable member 105 turns according to the switching operation of the shift lever and the movable-side contacts 111 and the fixed-side contact 110 come into contact with each other and separate from each other.
In the automatic transmission switch 101 of this kind, to secure a contact pressure between the fixed-side contact 110 and the movable-side contacts 111, a spring member which biases the movable-side contact 111 toward the fixed-side contact 110 is provided in the movable member 105. In the automatic transmission switch 101 shown in FIG. 1, for example, a leaf spring 125 which biases the movable-side contacts 111 toward the fixed-side contact 110 is provided in the movable member 105 (for example, see the specification and FIG. 1 and 3 of U.S. Pat. No. 5,736,701).
Meanwhile, in the case of the automatic transmission switch 101, since the movable member 105 is connected to the automatic transmission, if the automatic transmission receives vibration from an engine during running of the vehicle and vibrates, the vibration is transmitted from the automatic transmission directly to the movable member 105. If the vibration of the automatic transmission which transmitted to the movable member 105 is propagated to the movable-side contact 111 through a spring member (the leaf spring 125), deformation of the spring member can not follow the vibration, and the movable-side contacts separate from the fixed-side contact 110 in some cases. That is, if vibration of the automatic transmission is propagated to the movable-side contacts 111 through the spring member, a so-called bounce is generated in the movable-side contacts 111 and there is a possibility that contact failure is generated between the movable-side contacts 111 and the fixed-side contact 110.